@article{JETPL.109.651, title = {}, author = {Punegov, V. I.}, journal = {JETP Lett.}, volume = {109}, issue = {10}, pages = {628}, year = {2019}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.1134/S0370274X19100023}, note = {[Pisma v ZhETF 109, 651 (2019)]} }